The foremost research objectives of this continuing project involve the conception and preparation of new materials that are specifically designed for use in the practice of preventive and restorative dentistry. Increases in the durability and reliability of materials for the obturation of pits and fissures will be made posible by the development of recently conceived and synthesized adhesion-promoting compounds, and the optimization of procedures for their use in clinical dentistry. Major improvements in hydrolytic and mechanical stability of the bonding between these materials and hard tooth tissues are expected from the combined use of: (1) an acid to etch the surface; (2) a mordant to exchange surface calcium ions with certain metal ions; and (3) polyfunctional surface-active comonomers to form heterocyclic chelate rings with more than one surface-bound metallic ion, and to homopolymerize or copolymerize with suitable dimethacrylate monomers. The utilization of new reinforcing fillers with improved means of bonding to the polymeric phase of preventive and restorative dental materials should yield better wear resistance to composite resins. Analgous means to obtain durable adhesion between restorative materials and dentin, exposed at the gingival or root surfaces of teeth (due to gingival recession, cervical abrasion or erosion, or carious processes), will be pursued.